tbuckley/cabot-search huggingface dataset:
EXTH-03. HSP90 INHIBITION OVERCOMES RESISTANCE TO MOLECULAR TARGETED THERAPY IN BRAFV600E MUTANT HIGH-GRADE GLIOMA
Authors: Kensuke Tateishi, Jo Sasame, Ikegaya Naoki, Manabu Natsumeda, Masahito Kawazu, Hiroaki Wakimoto, Daniel Cahill, Tetsuya Yamamoto
Journal: Neuro-Oncology (2022)

Abstract INTRODUCTION Molecular targeted therapy using BRAF and/or MEK inhibitors has been applied to BRAFV600E mutant high-grade gliomas (HGGs); however, the therapeutic effect is limited by the emergence of drug resistance. METHODS We established multiple paired BRAFV600E mutant HGG patient-derived xenograft (PDX) models based on tissues collected prior to and at relapse after molecular targeted therapy. Using these models, we dissected treatment resistant mechanisms for molecular targeted therapy and explored therapeutic targets to overcome resistance in BRAFV600E HGG models in vitro and in vivo. RESULTS We found that, despite causing no major genetic and epigenetic changes, BRAF and/or MEK inhibitor treatment deregulated multiple negative feedback mechanisms, which led to the re-activation of the MAPK pathway through c-Raf and AKT signaling. This altered oncogenic signaling primarily mediated resistance to molecular targeted therapy in BRAFV600E mutant HGG. To overcome this resistance mechanism, we performed a high-throughput drug screening to identify therapeutic agents that potently induce additive cytotoxicity with BRAF and MEK inhibitors. We discovered that HSP90 inhibition combined with BRAF/MEK inhibition coordinately deactivated the MAPK and AKT/mTOR pathways, and subsequently induced apoptosis via dephosphorylation of GSK3β (Ser9) and inhibition of Bcl-2 family proteins. This mediated potent cytotoxicity in vitro and in vivo in refractory models with acquired resistance to molecular-targeted therapy. CONCLUSIONS The combination of an HSP90 inhibitor with BRAF or MEK inhibitors can overcome the limitations of the current therapeutic strategies for BRAFV600E mutant HGG.
TMIC-70. HARMONIZED SINGLE-CELL LANDSCAPE, INTERCELLULAR CROSSTALK AND TUMOR ARCHITECTURE OF GLIOBLASTOMA
Authors: Cristian Ruiz-Moreno, Sergio Marco Salas, Erik Samuelsson, Sebastian Brandner, Mariette Kranendonk, Mats Nilsson, Hendrik Stunnenberg
Journal: Neuro-Oncology (2022)

Abstract Glioblastoma (GBM) is the most aggressive and deadliest brain tumor in adults. Single-cell RNA sequencing (scRNA-seq) has helped to grasp the complexity of the cell states and dynamic changes within the tumor microenvironment (TME). To better capture the molecular underpinnings of transcriptomic variation across different individuals and reconstruct the intricate TME, it is necessary to gather a significant cohort that can empower our understanding of the complex GBM biology. In addition, little is known about the spatial disposition of the cells within the tumor, neighboring patterns, and intercellular crosstalk. Taking advantage of the recent developments in computational methods, we set out to build the GBM cellular landscape and created the ‘GBM-VERSE’, a curated reference that combines 16 datasets, and 113 patients spanning over 330 thousand cells. Our resource characterizes cells at different levels (coarse and detailed), identifying gene programs that define each cell type/state and providing a harmonized annotation. We demonstrated the applicability of the GBM-VERSE to map for newly generated data, providing a robust annotation tool for other GBM scRNA-seq datasets. We expanded the GBM-VERSE through transfer learning which increased the likelihood of identifying under-represented phenotypic states and incorporating cell types that were not present in the core reference. From the biological point of view, the GBM-VERSE facilitated the construction of an inferred global map of the cell-cell interactome. Our analysis highlighted the crucial role of MES-like cancer cells as the primary source of pro-angiogenic signaling. We employed the GBM-VERSE to chart the spatial architecture of GBM by deconvolving next-generation sequencing-based ST data. We found a well-defined spatiotemporal distribution of the neoplastic cells that were further inspected using an in situ sequencing-based platform. The GBM-VERSE represents a framework that allows the streamlined integration, and interpretation of new data and provides a platform for exploratory analysis, hypothesis generation, and testing.
EXTH-77. TARGETING CD73 IN GBM SENSITIZES TUMORS TO ONCOLYTIC VIRUS THERAPY
Authors: Sara Murphy, Matthew P Mullarkey, Upasana Sahu, Bangxing Hong, Cole Lewis, Miguel Diaz, Pamela Wenzel, Abu Hena Mostafa Kamal, Nagireddy Putluri, Junhyoung Park, Benny Kaipparettu, Balveen Kaur
Journal: Neuro-Oncology (2022)

Abstract Glioblastoma Multiforme (GBM) is the most aggressive malignant primary brain tumor and has abysmal 5-year overall survival. With the approval of oHSV Imlygic by FDA for metastatic melanoma and more recently, conditional approval of G47Δ, marketed by Daiichi Sankyo for GBM treatment in Japan, oncolytic viral therapy has emerged as a promising biological approach to treat solid tumors. Our laboratory has previously shown that oHSV expressing long isoform of PTEN (PTENα), HSV-P10, has faster kinetics of virus replication associated with enhanced killing of the glioma cells compared to control HSV. Additionally, HSVP-10 is known to increase mitochondrial membrane potential and cellular ATP production while stimulating anti-tumor immune responses in vivo. RNA sequencing of primary GBM cells infected with HSV-P10 shows altered metabolic pathways relative to control HSV infected cells. 13C metabolic flux analysis in uninfected and control or HSV-P10 infected primary GBM cells reveals that while HSV-P10 infection shuttles most of the glutamine towards citrate by reductive carboxylation of α-ketoglutarate resulting in faster replication of HSV-P10, simultaneously it increased glucose utilization and shuttling towards TCA cycle. This corroborates with enhanced mitochondrial activity leading to increased oxidative phosphorylation and increased cellular and extracellular ATP (eATP). eATP binds to purinergic receptors on tumor and immune cells and boosts anti-tumor immunity. However, the use of extracellular ATP in cancer therapy is limited owing to its short half-life and rapid hydrolysis by ectoenzymes CD39 and CD73 into immune-suppressing adenosine. CD73 carries out the conversion of AMP to adenosine, making it a key regulator of this pathway. Using mice with CD73 knocked out globally (CD73KO), we show that combination of CD73 inhibition with HSV-P10 imparts significant survival benefit compared to WT mice treated with HSV-P10. Our findings will further the understanding of oHSV therapy and the role of the ATP/adenosine in the tumor microenvironment.
EXTH-81. ITGA5 IS A NOVEL IMMUNOTHERAPEUTIC TARGET AGAINST TREATMENT REFRACTORY MEDULLOBLASTOMA
Authors: David Bakhshinyan, Yujin Suk, Laura Kuhlman, Ashley Adile, Vladimir Ignatchenko, William Gwynne, Stefan Custers, Andrew Macklin, Chitra Venugopal, Thomas Kislinger, Sheila Singh
Journal: Neuro-Oncology (2022)

Abstract Medulloblastoma (MB) is the most common type of malignant pediatric brain cancer. Current standard of care (SOC) involves maximal safe resection and neuraxis radiotherapy and chemotherapy in individuals older than 3 years. To date, these cytotoxic SOC combined with craniospinal irradiation led to devastating neurocognitive and developmental deficits impacting quality of life for pediatric patients. The biological heterogeneity of MB is highlighted by the existence of four distinct molecular subgroups (WNT, SHH, Group 3, and Group 4). Group 3 and Group 4 have the poorest patient outcomes because of their aggressive, metastatic nature, and so often remain treatment refractory to SOC. Group 3 has a poor prognosis due to its high incidence of leptomeningeal spread and an overall survival rate of less than 50%. The cytotoxic nature and lack of response in specific subtypes to SOC underscores the urgent need for developing and translating novel treatment options including immunotherapies. In our earlier work, we have developed a therapy-adapted patient derived xenograft (PDX) model of the Group 3 MB as the tumor cells undergoes therapy in vitro and in vivo. N-glycocapture surfaceome profiling of the MB cells through this PDX model identified Integrin α5 (ITGA5) as one of the most differentially expressed targets found at recurrence when compared to engraftment and untreated timepoints. Through shRNA knockdown and small molecule inhibition, we identify ITGA5 expression marks a MB cell subpopulation with increased self-renewal ability both in vitro and in vivo. Access to recurrent MB (rMB) post-therapy allowed us to investigate the changes in the surfaceome of MB cells using proteomics profiling to identify promising rMB-specific targets for rational development of novel immunotherapies.
NCMP-11. METASTATIC MENINGIOMA: AN UNUSUAL COURSE OF A COMMON DISEASE
Authors: Danielle Bazer, Ewa Zabrocka, Marielle Torres, Ariana Frontario, Agnieszka Kowalska
Journal: Neuro-Oncology (2022)

Abstract BACKGROUND The most common central nervous system (CNS) tumor in adult patients is meningioma, accounting for 30% of all intracranial tumors. Despite this, extracranial meningioma metastases are exceedingly rare, accounting for 0.1% of cases, with common locations for metastases localized to the lungs, liver, lymph nodes, and bone. RESULTS We present a 55-year-old female with a past medical history of tobacco use, hypertension and depression, who initially presented due to a generalized tonic-clonic seizure. MRI brain revealed an intracranial lesion in the left occipital lobe with mass effect, requiring craniotomy and resection. Pathology was consistent with WHO grade I meningioma and post-operatively a small area of residual tumor remained. PET/CT found a left lung nodule, which was thought to be due to her smoking history and was followed with annual scans. Four years later, she had an increase in the size of the meningioma on surveillance MRI scans. The patient then required repeat craniotomy which redemonstrated pathology of WHO grade I meningioma, then treated with stereotactic radiation 14 Gy. The subsequent annual surveillance pulmonary scan showed a growth of left pulmonary nodule. She underwent a left lingual wedge resection and was found to have low grade spindle cell tumor, consistent with metastatic meningioma. CONCLUSION Although rare, metastatic meningioma should be included in the differential diagnosis of patients with concomitant extracranial lesions. Our case highlights the importance of annual, surveillance scans of extracranial lesions in meningioma patients.
EXTH-72. TTFIELDS ENHANCE THE ANTINEOPLASTIC ACTIVITY OF THE DRUG-REPURPOSING APPROACH CUSP9V3 IN GLIOBLASTOMA IN VITRO
Authors: Qiyu Cao, Annika Hajosch, Richard Kast, Michal Hlavac, Mike-Andrew Westhoff, Markus Siegelin, Christian Rainer Wirtz, Marc-Eric Halatsch, Georg Karpel-Massler
Journal: Neuro-Oncology (2022)

Abstract OBJECTIVE Drug repurposing represents a promising strategy to safely accelerate the clinical use of therapeutics with antineoplastic activity. In this study, we examined whether Tumor Treating Fields (TTFields) enhance the biological effects of CUSP9v3, a treatment strategy including nine repurposed drugs, in an in vitro setting of glioblastoma. METHODS We performed MTT-assays to examine effects of the combination treatment on the viability of different glioblastoma cells. Tumor spheroids were used as a model to examine effects of the combination treatment in a 3-dimensional setting. Staining with annexin V/propidium iodide or MitoTrackerTM followed by flow cytometry was done to assess pro-apoptotic effects. Specific protein expression of caspases and members of the Bcl-2 family of proteins was determined by Western blot analyses. RESULTS TTFields had at least additive inhibitory effects on the cell viability of established (U251), primary cultured (PC38, PC40, PC128) and stem-like (SC38, SC40) glioblastoma cells when combined with CUSP9v3. In addition, flow cytometric analyses revealed that a simultaneous treatment with TTFields and CUSP9v3 significantly increased the fraction of annexin V-positive (apoptotic) glioblastoma cells. Moreover, the fraction of cells with a reduced mitochondrial outer membrane potential was significantly higher following a simultaneous treatment with TTFields and CUSP9v3. On the molecular level, these observations were associated with enhanced cleavage of effector caspase 3 and a reduced expression of the anti-apoptotic Bcl-2 family proteins Bcl-2 and Mcl-1. CONCLUSION These data suggest that TTFields enhance the susceptibility of glioblastoma cells towards CUSP9v3, potentially allowing significant dose reduction and decreased toxicity. This observation seems to rely at least in part on a caspase-dependent cell death mechanism. TTFields are widely used for the treatment of glioblastoma patients and CUSP9v3 was recently shown to have a favorable safety profile in a phase Ib/IIa trial (NCT02770378) which facilitates transition of a combined approach to the clinical setting.
EXTH-11. TELOMERASE INHIBITION IS AN EFFECTIVE THERAPEUTIC STRATEGY IN TERT PROMOTER-MUTANT GLIOBLASTOMAS MODELS WITH LOW TUMOR BURDEN
Authors: Lauren Kageler, Elisa Aquilanti, Jacqueline Watson, Duncan Baird, Rhiannon Jones, Marie Hodges, Patrick Y Wen, Matthew Meyerson
Journal: Neuro-Oncology (2022)

Abstract Glioblastoma targeted therapeutics have been challenging to develop due to significant inter- and intra-tumoral heterogeneity. While many activated oncogenes in glioblastoma are subclonal, TERT promoter mutations commonly occur as clonal events and are found in up to 80% of IDH-wildtype glioblastomas. Given the high prevalence and clonal nature of TERT promoter mutations in glioblastoma, telomerase is considered a promising therapeutic target for this deadly cancer. Prior studies have validated this hypothesis, demonstrating that knockout of the transcription factor GABPA, which selectively binds to the mutant TERT promoter, as well as base editing-mediated correction of TERT promoter mutations, are selectively toxic to TERTpromoter mutant glioblastomas. However, an important limitation of this strategy is that cancer cell death does not occur immediately after telomerase ablation, but rather after several cell divisions required to reach critically short telomeres. We therefore hypothesize that telomerase inhibition would only be effective in low tumor burden glioblastomas. In this study, we used CRISPR interference to knock down TERT expression in TERT promoter-mutant glioblastoma cell lines and patient derived models. We then measured cell viability and assessed for features of telomere crisis by measuring telomere length and chromatin bridge formation. Lastly, we used a doxycycline inducible CRISPR interference system to knock down TERT expression in vivo early and late in the tumor formation process. We demonstrated that TERT promoter-mutant glioblastoma cells are sensitive to telomerase inhibition and undergo telomere crisis. In vivo, tumor formation is only inhibited when TERT knockdown is induced shortly after tumor implantation, but not when tumor burden is high. This work supports the idea that telomerase inhibition would be a suitable therapeutic strategy for glioblastoma patients with low tumor burden, for example in the adjuvant setting after surgical debulking and chemoradiation.
TMIC-11. ASSOCIATION OF TIM-3/GAL-9 AXIS WITHNLRC4 INFLAMMASOME IN GLIOMA MALIGNANCY: TIM-3/GAL-9 INDUCE THE NLRC4 INFLAMMASOME
Authors: Jeongmin Sim, JeongMan Park, Suwan Kim, Sojung Hwang, KyoungSu Sung, Jung-Eun Lee, SeungHo Yang, Kyunggi Cho, SungHwan Lee, Jong-Seok Moon, Juwon Ahn, Jaejoon Lim
Journal: Neuro-Oncology (2022)

Abstract Tim-3/Gal-9 and the NLRC4 inflammasome contribute to glioma progression. However, the underlying mechanisms involved are unclear. Here, we observed that Tim-3/Gal-9 expression increased with glioma malignancy and found that Tim-3/Gal-9 regulate NLRC4 inflammasome formation and activation. Tim-3/Gal-9 and NLRC4 inflammasome-related molecule expression levels increased with WHO glioma grade, and this association was correlated with low survival. We investigated NLRC4 inflammasome formation by genetically regulating Tim-3 and its ligand Gal-9. Tim-3/Gal-9 regulation was positively correlated with the NLRC4 inflammasome, NLRC4, and caspase-1 expression. Tim-3/Gal-9 did not trigger IL-1 secretion but were strongly positively correlated with caspase-1 activity as they induced programmed cell death in glioma cells. A protein– protein interaction analysis revealed that the FYN-JAK1-ZNF384 pathways are bridges in NLRC4 inflammasome regulation by Tim-3/Gal-9. The present study showed that Tim-3/Gal-9 are associated with poor prognosis in glioma patients and induce NLRC4 inflammasome formation and activation. We proposed that a Tim-3/Gal-9 blockade could be beneficial in glioma therapy as it would reduce the inflammatory microenvironment by downregulating the NLRC4 inflammasome.
NCMP-22. TREATING PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY (PML) WITH PEMBROLIZUMAB: A SINGLE INSTITUTION EXPERIENCE
Authors: Sebastian Hanna, Alissa Thomas
Journal: Neuro-Oncology (2022)

Abstract BACKGROUND PML is a rapidly progressive demyelinating disease, occurring in immunocompromised patients due to the opportunistic JC virus. The highest mortality rates are seen among patients with cancer treated with immunosuppressive therapy and for whom immune reconstitution is not possible. In 2019, the National Institutes of Health reported clinical benefit in patients with PML treated with pembrolizumab. We report our institutional experience with pembrolizumab for three patients with PML after exposure to rituximab and other chemotherapy. CASE PRESENTATION: The first patient was a 75-year-old woman with a history of psoriatic arthritis and bullous pemphigoid treated with rituximab. Eight months after rituximab exposure she presented with right hemiparesis and word-finding difficulty. PML was diagnosed based on positive JC virus DNA in cerebrospinal fluid by PCR. She received two doses of pembrolizumab with improvement in her neurological symptoms. Shortly after her second dose she contracted COVID-19 and died at her nursing home. The second patient was a 47-year-old man with a history of T cell/histiocyte large B-cell lymphoma treated with R-CHOP with salvage DHAP chemotherapy followed by BEAM and autologous stem cell transplant, with complete remission. Seven months post-transplant he presented with a rapidly progressive hemianopsia and aphasia, and PML was confirmed by brain biopsy. He received one dose of pembrolizumab but worsened and died of neurological deterioration secondary to PML. The third patient was a 73-year-old man with a history of mantle cell lymphoma previously treated with rituximab and bendamustine, who presented with acalculia and aphasia 14 months after rituximab exposure. PML was confirmed by brain biopsy, and he was treated with pembrolizumab with improvement in his neuro-cognitive functioning. CONCLUSIONS We observed neurological improvement following pembrolizumab treatment for PML in two of three patients, with one patient experiencing a durable response that is ongoing 3 years following PML diagnosis.
RADT-28. MULTI-SESSION RADIOSURGERY FOLLOWING SURGERY FOR INTRACRANIAL MENINGIOMAS: 10-YEAR OUTCOMES FROM A SINGLE INSTITUTION PROTOCOL
Authors: Michael Carrasquilla, Jonathan Cantalino, Kathryn Hay, Kelsi Chesney, Anousheh Sayah, Emily Sloan, Joseph Watson, Amjad Anaizi, Walter Jean, Kevin McGrail, Sean Collins, Brian Collins
Journal: Neuro-Oncology (2022)

Abstract INTRODUCTION Meningioma is the most common adult primary intracranial tumor. Surgical resection is the favored treatment with radiotherapy often utilized for residual or recurrent disease. Long-term outcomes are well-established for single-session radiosurgery but mature outcomes for multisession radiosurgery do not yet exist. We report our institution’s 10-year efficacy and toxicity outcomes for 5-fraction radiosurgery following surgical resection of intracranial meningiomas. METHODS All intracranial meningioma patients treated at our institution between 2002-2018 with 5-fraction radiosurgery following surgery were eligible for inclusion. Standard variables were analyzed to predict local failure and overall survival. RESULTS Forty-one consecutive patients with a female predominance (76%) and median age of 58 years (range: 27–84) were included. Thirty benign (73%) and 11 atypical meningiomas (27%) with a median gross tumor volume of 7.79cc (range: 0.38-52.63) were treated. All patients completed radiosurgery for residual tumor (41%) or recurrent disease (59%). A median dose of 3000cGy (range: 2500-3500cGy), was delivered to a median isodose line of 82% (range: 71%-90%). The median follow-up from the date of surgery was 10 years. Nine tumors (22.0%) progressed following radiosurgery. The local control rate at 10-years was significantly better for benign tumors than atypical tumors (93% vs 27%, p = 0.001). Factors found to be predictive of local failure on multivariate analysis were tumor grade (HR: 13.8, p = 0.002) and tumor volume (HR: 1.08, p = 0.031). For benign tumors all failures occurred at the margin of the unirradiated tumor bed, while atypical tumors failed predominately in-field (71%). Three patients with atypical meningioma developed radiation necrosis following aggressive treatment (3500cGy). Overall survival at 10-years was 93% for benign tumors and 60% for atypical tumors (p = 0.026). CONCLUSION Multisession radiosurgery following surgery for benign intracranial meningiomas provides excellent long-term tumor control with minimal toxicity. However, for atypical meningiomas this approach results in poor local control.